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"""Astroid hooks for understanding functools library module."""
import astroid
from astroid.interpreter import util as interpreter_util
from astroid.interpreter import objects
from astroid.interpreter import objectmodel
from astroid.test_utils import extract_node
from astroid import MANAGER
LRU_CACHE = 'functools.lru_cache'
class LruWrappedModel(objectmodel.FunctionModel):
"""Special attribute model for functions decorated with functools.lru_cache.
The said decorators patches at decoration time some functions onto
the decorated function.
"""
@property
def py__wrapped__(self):
return self._instance
@property
def pycache_info(self):
cache_info = extract_node('''
from functools import _CacheInfo
_CacheInfo(0, 0, 0, 0)
''')
class CacheInfoBoundMethod(objects.BoundMethod):
def infer_call_result(self, caller, context=None):
yield interpreter_util.safe_infer(cache_info)
return CacheInfoBoundMethod(proxy=self._instance, bound=self._instance)
@property
def pycache_clear(self):
node = extract_node('''def cache_clear(): pass''')
return objects.BoundMethod(proxy=node, bound=self._instance.parent.scope())
class LruWrappedFunctionDef(astroid.FunctionDef):
special_attributes = LruWrappedModel()
def _transform_lru_cache(node, context=None):
# TODO: this needs the zipper, because the new node's attributes
# will still point to the old node.
new_func = LruWrappedFunctionDef(name=node.name, doc=node.name,
lineno=node.lineno, col_offset=node.col_offset,
parent=node.parent)
new_func.postinit(node.args, node.body, node.decorators, node.returns)
return new_func
def _looks_like_lru_cache(node):
"""Check if the given function node is decorated with lru_cache."""
if not node.decorators:
return False
for decorator in node.decorators.nodes:
if not isinstance(decorator, astroid.Call):
continue
func = interpreter_util.safe_infer(decorator.func)
if func in (None, astroid.Uninferable):
continue
if isinstance(func, astroid.FunctionDef) and func.qname() == LRU_CACHE:
return True
return False
MANAGER.register_transform(astroid.FunctionDef, _transform_lru_cache,
_looks_like_lru_cache)
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